Abstract: Elevated concentrations of extracellular reactive oxygen species (ROS) are hallmarks of inflammation, and decades of medical research have focused on suppression of these molecules to treat pathologies as diverse as rheumatoid arthritis, cancer, and atherosclerosis with mixed results. More recently, researchers have discovered that these same molecules are produced during the course of normal signal transduction. In order to effectively treat inflammation, we must understand these distinct roles for reactive oxygen species. I propose an innovative research program that will elucidate the role of hydrogen peroxide, a key ROS, in normal cell signaling through computational models and laboratory experiments. This research will lead to a new, quantitative understanding of ROS and facilitate the development of effective antioxidant treatments for inflammation. This project will use three complementary approaches to evaluate the complex regulatory role of hydrogen peroxide on receptor-induced signaling. First, we will develop computational network models describing redox regulation of proteins in time-dependent manner. Secondly, we are designing new methods to detect oxidative changes on multiple proteins simultaneously. These assays will allow investigation of the relationships between phosphorylation of signal transduction molecules and reversible thiol modifications. Finally, we have created a series of cell lines in which key components of the redox network have been perturbed that demonstrate augmentation and attenuation of receptor signaling. These lines will be used to systematically investigate the efficiency of three receptor networks - a pro-inflammatory cue (TNF-a), anti-inflammatory cue (TGF-[unreadable]) and antigenic response (TCR) - under different oxidative environments. The results of these studies will provide the first computational modeling platform capable of interpreting incongruous literature reports of oxidative effects on cellular information processing. This project leverages my unique experience at the interface of immunology, systems biology, and metabolism to address a fundamental mechanism of cellular regulation critical for a large class of therapeutic drugs. Public Health Relevance: Elevated concentrations of extracellular reactive oxygen species are a hallmark of inflammation. Antioxidant therapies aim to suppress these molecules for treatment of pathologies as diverse as rheumatoid arthritis, cancer, and atherosclerosis with limited success. This project investigates the changes in signaling that are caused by reactive oxygen species in immune cells with the goal of generating predictive models useful for new antioxidant therapies.